Courses

Composition and Analysis of Musts and Wines

General

Course Contents

Theoretical Part of the Course

  • Acid composition of musts & wines. The different forms of acidity. The concept of pH and its applications. Volatile acidity. Wines.
  • The organic acids of musts & wines. The basic organic acids. The mechanism of crystallization & precipitation of tartaric acid salts.
  • Alcohols and other volatile compounds. Ethyl alcohol. Other simple alcohols. Polyols. Fatty acids. The esters. Aldehydes, ketones & lactones.
  • The sugars. Glucose and Fructose. The other sugars. The chemical properties of sugars. Derivatives of sugars. The extracellular polysaccharides of microorganisms.
  • Colloidal must macromolecules. Pectins and polysaccharides. Pectinolytic enzymes.
  • Nitrogenous compounds. The various forms of Nitrogen in musts and wines. The amino acids. Proteins and the mechanism of protein clouding. Biological amines.
  • The phenolic components. The nature, character and properties due to the structure of polyphenolic compounds.
  • Anthocyanins and tannins of red wines. The biosynthesis of anthocyanins during grape ripening. The extractability of anthocyanins and tannins during winemaking.
  • Chemical and organoleptic properties of anthocyanins and tannins. The chemical reactions of polyphenolic compounds during the maturation and aging of wines. The color of the wines. The precipitation of pigments & the stability of the color of red wines.
  • Sulfuric anhydride in musts and wines. Forms of sulphite. Relationship of sulphite forms to wine pH.
  • Inorganic components of musts & wines. The solid residue. The ash. The anions. The cations.
  • Iron and the mechanism of iron turbidity. Copper and the mechanism of copper tarnishing. The heavy metals.
  • The compounds responsible for the primary – varietal – aromas. The terpenes. The derivatives C 13. The methoxy – pyrazines. Sulfur compounds. The evolution of primary aromas during the maturation and aging of wines.

Laboratory Part of the Course

  • Determination of density in must and wines. Methods: Standard (Density Meters) and Reference (Lykithos), calculation of sugars from density measurement.
  • Analytical determination of reducing sugars: a) Lane – Eynon method, b) Luff – School method.
  • Determination of Solid Residue in must and wines.
  • Alcohols A: Determination of ethyl alcohol by: a) diluters, b) Lyketh, c) oxidation (chemical determination).
  • Alcohols B: Methanol, Higher alcohols (n – propanol, isobutanol, amyl alcohol, isoamyl alcohol), glycerol, 2,3 butanediol.
  • Must and wine acids A’: Volumetric and active acidity (pH). Definition and importance of volatile acidity in wine products.
  • Must and wine acids B’: Determination of acids: tartaric, malic and lactic.
  • Determination of sulfuric anhydride in wine products: A: Conventional method, B: Reference method (sulfite apparatus).
  • Phenolic components of wines. Anthocyanins (Color characteristics). Tannins, Other phenolic components.
  • Inorganic components of musts and wines: Determination of ash in wines. Ash alkalinity.
  • Nitrogenous components of musts and wines. Proteins, Amino Acids, Vitamins, Biological Amines, etc.
  • Carbonyl compounds of musts and wines: Acetaldehyde, acetoin, diacetyl. Determinations: Enzymatic, Spectrophotometric, Gas chromatograph.
  • Wine esters. Importance of esters in wines and their determination by gas chromatography.
  • Primary aromatic components of wines: Terpenes. Determination by gas chromatography.
  • Aging fragrances. Wood compounds, Eugenol, Vanillin. Determination by gas chromatograph.

Educational Goals

Through the theoretical part of this course, students will familiarize themselves in depth with the particularly complex chemical composition of musts and wines.
They will understand the origin and importance of each chemical compound or group of compounds separately and the importance of the interaction of various compounds or groups of compounds with each other.
Through the deeper knowledge of this course, students will be able to direct the vinifications in such a way as to favor – or on the contrary prevent – the synthesis or the expression of desirable or undesirable chemical compounds respectively.
At the same time, they will acquire the ability to perceive, through the chemical composition of a wine, information about the history, technology and organoleptic response of the specific wine.

After the end of the course students will be able to:

  • They know in depth the complex chemical composition of musts and wines.
  • They understand the origin and importance of each individual chemical compound or group of compounds as well as the importance of the interaction of various compounds or groups of compounds with each other.
  • They can direct the vinifications in such a way as to favor – or on the contrary prevent – the synthesis or the expression of desirable or undesirable chemical compounds respectively.
  • Perceive, through the chemical composition of a wine, information about the history, technology and organoleptic response of the particular wine.
  • hey become familiar with reading/understanding scientific papers.

General Skills

  • Autonomous work.
  • Teamwork.
  • Decision making.
  • Exercise criticism and self-criticism.
  • Promotion of free, creative and inductive thinking.

Teaching Methods

  • In the classroom, face to face.

Use of ICT means

  • Use of ICT in both course delivery and laboratory training in order to stimulate dialogue with students and develop their critical thinking.
  • Supporting the learning process through the e-class electronic platform.

Teaching Organization

ActivitySemester workload
Lectures26
Laboratory practice26
Study and analysis of bibliography18
Essay writing55
Total125

Students Evaluation

The exam  includes:

  1. Written exam for the theoretical part (50%):
    • Includes short answer questions,
    • development questions.
  2. Written exam for the laboratory part (40%):
    • Includes preparation of a laboratory exercise,
    • preparation of a laboratory report,
    • oral examination.
  3. Laboratory reports (10%)

Recommended Bibliography

  1. Επίσημη Εφημερίδα της Ευρωπαϊκής Ένωσης Κατάλογος και περιγραφή των μεθόδων ανάλυσης 2010/C 43/01 ISSN 1725-2423.
  2. Σταυρούλα Κουράκου – Δραγώνα. «Θέματα Οινολογίας». Τροχαλία, Αθήνα 1998.
  3. Ευάγγελος Σουφλερός. «Οινολογία. Επιστήμη και τεχνογνωσία». Copyright © 1997.
  4. Ευάγγελος Σουφλερός. «Οίνος και Αποστάγματα». Copyright © 1997.
  5. Αργύρης Τσακίρης. «Οινολογία. Από το σταφύλι στο κρασί». ΕκδόσειςΨύχαλος. Αθήνα 1998.
  6. Andrew L. Waterhouse , Gavin Sacks , David Jeffery “Χημεία και Βιοχημεία Οίνου: Οινοποίηση” Εκδόσεις Rosili 2019
  7. Pascal Ribéreau – Gayon, Yves Glories, Alain Maujean, Denis Dubourdieu. “Traité d’ OEnologie (Vol.2)”. Dunod, Paris 1998.
  8. Ron S. Jackson. “Wine science. Principles and applications”. Academic Press, Inc. California, 1994.
  9. Emile Peynaud. “Connaissanceet travail du vin”. Dunod, Paris 1981.
  10. OIV Compendium of International Methods of Analysis of Wines and Musts

Related Research Journals

  1. American Journal of Enology and Viticulture,
  2. Oeno One,
  3. Journal of the Science of Food and Agriculture,
  4. Agricultural and Food Chemistry,
  5. Food Chemistry,
  6. Beverages,
  7. South African Journal of Enology and Viticulture,
  8. Australian Journal of Grape and Wine Research.